1. Field of the Invention
The present invention relates to an adjustable reference current generator, a semiconductor device including an adjustable reference current generator and an adjustable reference current generating method.
2. Description of the Related Art
In recent years, with the spread of mobile devices, it is desired to prolong life of batteries. Therefore, it is an important technical target to lower a power consumption rate of components of the mobile devices in order to lower a power consumption rate of the respective mobile devices. For example, such mobile devices includes a reference current generator which generates a minute electric current of nA (nanoampere: 10^-9 A) order. The reference current generator is formed in a semiconductor integrated circuit such as CMOS (Complementary Metal Oxide Semiconductor) LSI.
Since such a reference current generator is subjected to variations in its characteristics caused within manufacturing process thereof. Since variations in characteristics of the reference current generator is large, it is required to adjust an instantaneous value of the reference current while measuring the instantaneous current value of the reference current. Measurement is performed after converting a current value into a voltage value. For example, a voltage having a voltage value corresponding to a current value is generated by connecting a constant current source and a diode-connected transistor and by outputting a partial pressure. (For example, Japanese patent application Laid-Open No. 2010-278854).